Any filtering separator which is able to be remove aerosols or other undesired suspended matter such as pathogens, pollen, dusts or gases from the air is designated as an air filter. Typically, fibres or grains come into use as filter medium or collector of a generic air filter.
DE 101 11 318 A 1 discloses a filter device for equipping a ventilation and/or heating and/or air-conditioning system, in particular for motor vehicles, which comprises a frame which surrounds at least partially a flexible and deformable filter medium: The frame consists of a flexible and deformable thermoplastic elastomer and is fastened by forming on the filter medium; it comprises two side walls of small thickness, the inner surfaces of which are provided with elevations which surround the longitudinal edges of the filter medium.
DE 198 16 238 A 1 proposes a reinforcement strip for a plate-shaped filter element with filter web material folded in a zigzag shape, which with an ability of the filter element to be curved provides for a reciprocal fixing in position of the folds. A reinforcement strip having the following features is intended to serve this purpose: The reinforcement strip is constructed in the form of a comb with a continuous longitudinal crosspiece and with teeth proceeding therefrom; the teeth of the comb are suitable for the substantially form-fitting receiving of the folds of the filter web material; pairs of teeth spaced apart from one another, consisting of adjacent teeth, are constructed as spring clips for a force-fitting clamping respectively of a fold of a filter web material; the longitudinal crosspiece of the reinforcement strip is flexible elastically in the longitudinal plane spanned by the teeth, whilst it is constructed so as to be considerably more rigid against lateral bending.